Breakthrough Alzheimer’s Drug Associated With Deadly Side Effect, New Study Shows

(DOMINICK REUTER/AFP via Getty Images)

Dylan Housman Deputy News Editor
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Lecanemab, a breakthrough drug developed to treat Alzheimer’s, caused an alarming rate of brain swelling in a new clinical trial.

The experimental drug developed by Eisai and Biogen was effective in slowing the cognitive decline brought on by the disease, but was also associated with brain swelling in nearly 13% of patients, according to data released Tuesday by the companies. Five patients also suffered macrohemorrhages in the brain and 14% suffered microhemorrhages, Axios reported.

Two patients who received the drug died during a follow-up study. The trial included almost 1,800 participants in total and took place over the course of 18 months.

Despite the serious possible side effects, the Alzheimer’s Association still called on the Food and Drug Administration (FDA) to grant the drug accelerated approval. Patients saw improvements ranging from 23% to 37% in certain measures of cognition and daily function.

Researchers believe the drug could be more effective the earlier it’s taken in the development of the disease. It does not reverse the damage already done by Alzheimer’s, but has shown in multiple trials to slow its progression. (RELATED: Alzheimer’s Drug Manufacturer Under Federal Investigation For Allegedly Falsifying Research: REPORT)

Biogen and Eisai announced initial trial results in September, which showed Lecanemab to be the first drug ever to slow the progression of Alzheimer’s.

The FDA is set to determine by Jan. 6 whether or not it will grant the drug accelerated approval. Accelerated approval requires a treatment to provably impact the biomarkers associated with a particular disease.